With developments of a digital technology, an image compression processing technology, and high-speed computer communication and optical communication technologies, image information transmission in a broadband becomes possible, and thus a free bidirectional service has been already implemented on an Internet. Further, unlike a conventional Pay Per View (PPV) service where a subscriber demands a program and waits, a bidirectional image service where the subscriber immediately selects and views a desired program at a desired time, that is, a Video On Demand (VOD) service is provided. Particularly, due to activations of an IPTV and UCC, the VOD service has been actively used after the 2000's.
Meanwhile, a conventional VOD service adopts a Hard Disk Drive (HDD) for performing read/write in a mechanical manner as a storage device, so that a read/write speed is slow, and accordingly one HDD based server supports speeds only in a range substantially from 1 Gbps to 1.5 Gbps (giga bit per second).
In order to solve such HDD problems, a Solid State Drive (SSD) including a semiconductor memory such as a DRAM or NAND memory to purely electronically perform read/write has been proposed, and the SSD can perform the read/write at a greatly faster speed in comparison with the HDD since the SDD operates in an electronic manner. Accordingly, various attempts to provide the VOD service using the SSD as the storage device are currently made.
Meanwhile, substantially 1,500 bytes are transmitted per one packet on the network in the VOD service, and an operation system of the server manages the CPU to process one packet for each session, that is, to read one packet for each session from the storage device and transmit the read packet to a requester client through the network.
Accordingly, although a conventional VOD server adopts an SSD storage capable of sufficiently supporting a read/write speed equal to or faster than 10 Gbps, the CPU should process substantially 800,000 (10,000,000/1,500) commands per second to provide the 10 Gbps service, so that an occupancy rate of the CPU increases to more than 90% and thus the CPU cannot perform another task such as a system management or the like at all, which makes only a service at a maximum speed of 5 to 6 Gbps possible.